1. Field of the Invention
The present invention relates to wireless IC devices and, in particular, to a wireless IC device including a wireless IC chip for use in an RFID (Radio Frequency Identification) system.
2. Description of the Related Art
RFID systems for transmitting information have recently been developed as a management system of goods. In such an RFID system, a reader/writer generating an induction electromagnetic field communicates in a contactless fashion with an IC chip (also referred to as an IC tag or a wireless IC chip) storing predetermined information attached to goods or a container.
As disclosed in Japanese Unexamined Patent Application Publication No. 2005-244778, a wireless tag known as a wireless IC device includes an IC chip mounted thereon. The wireless tag includes a dipole antenna (including a pair of main antenna elements and a matching unit) on a piezoelectric substrate and a tag IC electrically connected to ends of the dipole antenna. The matching unit, arranged between the tag IC and the main antenna elements, has a function of matching impedances between the tag IC and the main antenna elements.
The wireless tag has a problem discussed below. When the tag IC is electrically connected to the dipole antenna, a connection terminal of a small tag IC needs to be accurately positioned with respect to the dipole antenna and then mounted. A high precision mounting apparatus is thus required to avoid connection failures. Matching units, each occupying a large area, need to be arranged for the pair of main antenna elements in a manner such that the matching units do not overlap the antennas. The size of the wireless tag may be increased.